Summary Statement: December 31, 1862 – New York Independent Batteries, Part 2

Earlier this week, I started on the long list of New York Independent Light Artillery Batteries, from the fourth quarter (December), 1862 summaries.  This second part of the list presents a lot more gaps to fill and questions to answer:

0067_Snip_Dec62_NY_Ind2_1

Notice this set of batteries, between the 15th and 32nd, is not complete.  So that’s one gap to address.  And we have only six returns logged in by the clerks, two of which were not posted until 1864.  We pick up with the 15th Independent Battery:

  • 15th Battery:  At Fredericksburg, Virginia with six 3-inch Ordnance Rifles.  The 15th was a re-designation of Battery A, 2nd New York Light Artillery Battalion (recall the 14th was a similar flip of Battery B of the same battalion).  The battery was assigned to the Artillery Reserve, under (temporary command of) Lieutenant Andrew R. McMahon but was not engaged during the battle of Fredericksburg. Captain Patrick Hart would assume command in February.
  • 16th Battery: In Washington, D.C. with six 10-pdr Parrott Rifles. Originally Dickinson’s Light Artillery, this battery was under Lieutenant Milo W. Locke and posted to the Artillery Camp of Instruction.
  • 17th Battery: Minor’s Hill, Virginia with six 12-pdr Napoleons.  Organized as the Orleans Battery in August 1862. Captain George T. Anthony’s battery was part of Abercrombie’s Division, defending Washington.
  • 18th Battery: No report.  The “Black Horse Artillery” or “Billinghurst Battery” in William Billinghurst and his proto-machine gun. Captain Albert Mack commanded this battery, which was in route to New Orleans in December 1862 to become part of the Department of the Gulf.  Reports indicate the battery was issued some of the Billinghurst-Requa guns.  However, a report from late January 1863 indicates the battery had six 20-pdr Parrotts.
  • 19th Battery: In Washington, D.C. with six 12-pdr Napoleons.   Posted to the Camp of Instruction under Captain William H. Stahl.
  • 20th Battery: No report. Captain  B. Franklin Ryer’s battery was still getting organized in December 1862 and would serve at Fort Schuyler, New York.
  • 21st Battery: No report. In December 1862 this battery was heading to New Orleans, under Captain  James Barnes.  The battery would be part of the garrison of that city.
  • 22nd Battery: Camp Barry, Washington, D.C. with six 12-pdr Napoleons. Captain John D. Numan commanded this short-lived light battery.  By February the battery became Company M, 9th New York Heavy Artillery.
  • 23rd Battery: Washington, North Carolina with six 3-inch Ordnance Rifles. And another long story that needs its own post!  This was originally Battery A, New York Rocket Battaion, which was sent to North Carolina in April 1862.  The re-designation was not official until later in 1863.  And obviously by December 1862 the rockets were replaced by conventional artillery.  Captain Alfred Ransom was in charge.
  • 24th Battery: No report. And this was Battery B of the Rocket Battalion.  Also serving in North Carolina, this battery was under Captain J. E. Lee.  And we might also assume the battery had, or was, exchanging rockets for muzzleloading artillery.
  • 25th Battery: No report.  The 25th was also heading to New Orleans in December 1862.  But this hard-luck battery lost most of its horses when the transport Sparkling Sea wrecked off Florida on January 9, 1863.  Captain John A. Grow commanded.

Not listed on this return are the 26th, 27th, and 28th Batteries.  Let us fill in the blanks:

  • 26th Battery: Captain George W. Fox’s battery had worse luck than the 25th, and wrecked twice before arriving in New Orleans in late January.
  • 27th Battery: Under Captain John B. Eaton, this brand-new battery was just arriving in Washington, D.C. at years’ end.
  • 28th Battery: Also just mustering in at the end of the year.  Captain Cyprian H. Millard had command during this period and the battery assigned to Fort Schuyler, New York.

As for the 29th, 30th, 31st, and 32nd Batteries, recall those four were, respectively, Batteries A, B, C, and D of the 1st New York Light Artillery.  New York would have four more numbered independent batteries, on paper at least.  But those are for consideration outside the reporting period.

With the administrative details out of the way, and hopefully some gaps in the summary explained, let us look to the ammunition reported.  First the smoothbore projectiles:

0069_Snip_Dec62_NY_Ind2_1

Three batteries with 12-pdr Napoleons:

  • 17th Battery: 292 shot, 112 shell, 236 case, and 168 canister.
  • 19th Battery: 288 shot, 96 shell, 288 case, and 96 canister.
  • 22nd Battery:  288 shot, 96 shell, 228 case, and 96 canister.

Of note, all three batteries were in or around Washington at the time.  So one might expect the ordnance supplies to be well dressed and orderly.

For Hotchkiss pattern rifled projectiles:

0069_Snip_Dec62_NY_Ind2_2

Two batteries for consideration:

  • 15th Battery: 365 percussion shell and 720 bullet shell for 3-inch rifle.
  • 23rd Battery: 336 shot, 50 canister, 60 percussion shell, 50 fuse shell, and 80 bullet shell for their 3-inch rifles. I like the assortment offered.

Next, entries for Dyer’s and Parrott’s patent projectiles:

0070_Snip_Dec62_NY_Ind2_1

The 15th Battery reported 120 Dyer canister for their 3-inch rifles.  The 16th Battery had 479 shell, 600 case, and 135 canister of Parrott pattern for their 10-pdr rifles from the same manufacturer.

None of the batteries reported Schenkl pattern projectiles:

0070_Snip_Dec62_NY_Ind2_2

And that brings us to the small arms:

0070_Snip_Dec62_NY_Ind2_3

By battery:

  • 15th Battery: 18 Navy revolvers and 19 cavalry sabers.
  • 16th Battery: 14 Army revolvers and 21 horse artillery sabers.
  • 17th Battery: 30(?) Army revolvers and 20 horse artillery sabers.
  • 19th Battery: 20 Army revolvers and 50 horse artillery sabers.
  • 22nd Battery: 18 Army revolvers and 20 horse artillery sabers.
  • 23rd Battery: 60 Army revolves and 75 cavalry sabers.

The eighteen New York batteries mentioned in today’s post we see varied service histories and several associated with the more exotic weapons from the Civil War.  This is yet another point I wish the summaries were more complete. Perhaps then we might track down more details of the service history of these lesser-known weapons.

Summary Statement: December 31, 1862 – New York Independent Batteries, Part 1

After looking at those New York light batteries within the regimental system (First and Third) and those in the lone light battalion, along with the “other” equipment assigned to non-artillery units, it is time to look at the number of batteries from New York given “independent” designations.  And… that is not a short list:

0067_Snip_Dec62_NY_Ind1_1a

To make these shorter posts, let us break the list into parts.  Here’s the first part of that, looking at the 1st through 14th:

0067_Snip_Dec62_NY_Ind1_1

Perhaps not a clean half in number, but I’ve already cut the snips.  Of the first fourteen listed, the clerks recorded eight returns.  Two of those were not received until 1864:

  • 1st Independent Battery: At Belle Plain, Virginia with six 3-inch Ordnance Rifles. We’ve already mentioned Captain Terrence J. Kennedy’s linked to Battery L, 3rd New York Light Battery in “rumor and innuendo.” Captain Andrew Cowan commanded the battery by December 1862 and supported Second Division, Sixth Corps, Army of the Potomac.
  • 2nd Independent Battery:  No return. Captain Louis Schirmer’s battery was assigned to the Eleventh Corps.  It would be broken up in June of 1863.
  • 3rd Independent Battery: At Potomac Creek, Virginia with four 10-pdr Parrotts. Supported Sixth Corps and led by Lieutenant William A. Harn.
  • 4th Independent Battery: No return.  Captain James Smith’s battery supported Second Division, Third Corps.  Please note that Lieutenant Joseph E. Nairn was in “executive command” of the battery while Smith held the post of battalion commander.  The battery had six 10-pdr Parrotts in action at Fredericksburg.
  • 5th Independent Battery: At Falmouth, Virginia with four 20-pdr Parrotts.   This was Captain Elijah D. Taft’s battery in the Army of the Potomac’s Artillery Reserve.
  • 6th Independent Battery: No return. Captain W. M. Bramhall’s battery was also part of the Artillery Reserve and would later be part of the Horse Artillery (under a new commander).  They had six 3-inch Ordnance Rifles.
  • 7th Independent Battery: At Norfolk, Virginia with six 3-inch Ordnance Rifles.  Captain Peter C. Regan’s battery supported the Seventh Corps.
  • 8th Independent Battery: At Gloucester Point, Virginia with six 3-inch Ordnance Rifles.  Part of the Fourth Corps left behind on the Peninsula, Captain Butler Fitch commanded this battery.
  • 9th Independent Battery: No return.  Captain Emil Schubert led this battery.  It was assigned to the defense of Washington and, at least for the reporting period, was listed at Fort Washington.
  • 10th Independent Battery: At Falmouth with six 12-pdr Napoleons.  Recruited as the 2nd Excelsior Battery, Captain John T. Bruen’s battery supported Third Division, Third Corps.
  • 11th Independent Battery: Also at Falmouth but with six 3-inch Ordnance Rifles.  Formed as a “flying battery” under Captain Albert Von Puttkammer, this battery also supported Third Division of Third Corps.
  • 12th Independent Battery: Posted to Washington, D.C. and reporting four 3-inch Ordnance Rifles. Under Captain William H. Ellis, this battery was assigned to the Artillery Camp of Instruction.
  • 13th Independent Battery: No return.  At the time commanded by Captain  Julius Dieckmann and part of Eleventh Corps.  I presume this battery was equipped with six 3-inch Ordnance Rifles.
  • 14th Independent Battery: No return.  Shall we call this a “phantom” battery?  The 2nd New York Light Artillery Battalion was never recruited to full manning.  So it was consolidated into two batteries (A and B) for the spring 1862 campaigns.  By the fall of 1862 both batteries were reconstituted as independent batteries.  Battery B became the 14th (and Battery A would be the 15th – remember for Part 2).  By the end of the year, all three sections of the 14th were assigned to other batteries (one to Battery B, 1st New York, another to Battery C, 4th US, and a third to Battery G, 4th US).

Of the fourteen batteries summarized here, nine were in the Army of the Potomac.  One, the 14th, was for all practical purposes in the same army, but detailed as parts.  Two were formerly of the Army of the Potomac, but serving in the Virginia tidewater.  And the last two batteries were part of Washington’s defenses.  Geographically concentrated.

Turning to the ammunition, we have one battery with smoothbores:

0069_Snip_Dec62_NY_Ind1_1

The 10th Battery had 288 shot, 96 shell, 288 case, and 96 canister for its 12-pdr Napoleons.

But the New Yorkers were thick on rifled cannon.  For the Hotchkiss patent projectiles, they reported thus:

0069_Snip_Dec62_NY_Ind1_2

Starting from the top:

  • 1st Battery:  129 canister, 211 percussion shell, 270 fuse shell, and 570 bullet shell for 3-inch rifles.
  • 7th Battery: 114 canister, 47(?) percussion shell, 259 fuse shell, and 715 bullet shell for their 3-inch rifles.
  • 8th Battery: 175 canister for 3-inch rifles.
  • 11th Battery: 156 canister, 428 percussion shell, and 290 fuse shell for the 3-inch rifle.
  • 12th Battery: 193 canister, 135 percussion shell, and 594 bullet shell for 3-inch rifle.

Moving over to the Dyers, James, and Parrott patent types:

0070_Snip_Dec62_NY_Ind1_1

The 8th Battery reported having 369 Dyer shell and 650 Dyer shrapnel for 3-inch rifles (to go with their Hotchkiss canister).  The 3rd Battery reported 325 Parrott shell and 313 Parrott case for their 10-pdr Parrott rifles.  And the 5th Battery had 45 Parrott shell and 56 Parrott canister for their big 20-pdr rifles.

As for Schenkl projectiles:

0070_Snip_Dec62_NY_Ind1_2

Mind the calibers here:

  • 1st Battery: 29 Schenkl 3-inch shell.
  • 3rd Battery: 81 Schenkl shell and 109 Schenkl canister for 10-pdr Parrott.
  • 8th Battery: 45 Schenkl 3-inch shell.
  • 11th Battery: 89 Schenkl 3-inch shell.

We see the 3rd Battery mixing up their ammunition lots a bit.

Lastly, we look at the small arms:

0070_Snip_Dec62_NY_Ind1_3

By battery:

  • 1st Battery: 28 Navy revolvers, eight cavalry sabers, and fifteen horse artillery sabers.
  • 5th Battery: 22 Army revolvers and 21(?) horse artillery sabers.
  • 7th Battery: 18 Navy revolvers and 26 horse artillery sabers.
  • 8th Battery: 14 Navy revolvers and fourteen horse artillery sabers.
  • 10th Battery: 24 Army revolvers, 130 Navy revolvers, and twelve horse artillery sabers.
  • 11th Battery: 20 Army revolvers and 22 cavalry sabers.
  • 12th Battery:  29 Navy revolvers and 113 cavalry sabers.

So… if you wanted a revolver, they you preferred a position with the 10th New York Independent. If you were fond of edged weapons, you might consider enlisting in the 12th.

Next we’ll look at the other half of these New York independent batteries.

Fortification Friday: Attention to the all important traverse!

Thus far as we’ve examined, in meticulous detail, how to address relief in the planning of a field fortification, we’ve focused on the parapets.  Getting those tailored would protect against direct fire against the defenders of a particular face – direct defilement as we call it.  Mentioned earlier, the works also needed reverse defilement to protect the backs of those defenders.  That was the job of the traverse.

Let us pause for the moment to explain the traverse. The traverse was an internal structure within a work which was designed to intercept enemy fires or reduce the impact of an explosion.  Traverses filled a number of vital functions within the works and there were a number of variations, based on those functions.  We see traverses along a line, designed to intercept flanking fire.  Traverses might form a secondary facing along a line.  We also see traverses as sort of a “backstop” behind a sallyport.  And also traverses situated around magazines could prevent a disaster caused by a lucky shot (or stray ember).  But here we are looking at traverses built within a salient and intended to block enemy fire from the rear of the face. Such are defilade traverses (though I would point out defilade traverses apply here to both reverse and enfilade defense).

Going back to our notional figures, thus far Mahan had instructed how to determine the height of the parapet.

PlateIIFig16C

That accomplished….

To determine the height of the traverse is the next step.  To do this, the height of the tread of the banquette is ascertained on the three poles, B,C,D, and a distance of nine inches is set off on each pole above the tread.  Between the points thus determined a cord is stretched, or if the distance be too great for this, two pickets may be placed between B and C, and a cord, or straight edge, be fastened to them in the required direction.

Please note the mark set off on these well used poles.  This mark is but nine inches above the banquette – that being the location where the defender stands to shoot over the parapet.  The intent is to build a defense which will prevent the enemy from firing on that piece of ground from the rear.

An observer is then placed at the pole F, and another places himself behind the line B C, so as to bring the cord, and the points O’ and F, in the field of vision; he then shifts the position of the eye until the cord is brought to touch the point O’; he then directs the observer at F to mark the point on the pole where it is intersected by the plane of vision.

This is somewhat confusing at first read, but remember that at this time in the construction of the works, the parapets and other structures were not yet built. So the observers are walking over what is relatively level space. Still, this is difficult to depict on the diagram without the risk of confusion to the reader…

PlateIIFig16D

Work with me here – we have the line marked off between A-B-C.  The second observer is somewhere there behind that line (and outside what would be come the works later on).  Then the second observer directs the positioning of our original line of F-C until that cord, along with cord A-B-C and the line to O’ all sit in the same plane.  That would determine the “mark” used as the baseline for the traverse. (I know what you are thinking… nine inches?  Hold on to that for a second.)

Mahan continued:

A similar operation is performed with the point O, and the face C D, and above the highest point thus determined on F, a distance of five feet is set off for the top of the traverse at F; and five feet nine inches is set off above the tread of the banquette at C for the top of the traverse at that point.

So, pick the highest of the two baseline marks, add five feet to cover the backs of the standing musket-firing infantryman, and you have the desired height the traverse. Oh, and with that we have a new term to use:

The planes which determine the top of the traverse, are termed planes of reverse defilement.

That’s good because, as you probably have figured out, fortifications are built upon a firm foundations of technical terminology.  The more buzzwords the engineer offered, the better the fort.

The height established, there were other details needed to finalize the traverse:

The traverse is finished on top like the roof of a house, with a slight pitch; its thickness at top should seldom exceed ten feet, and will be regulated by the means the enemy can bring to the attack; its sides are made with the natural slope of the earth; but, when the height of the traverse is considerable, the base of the side slopes would occupy a large portion of the interior space; to remedy this, in some measure, the portion of the sides which are below the planes of direct defilement, may be made steeper than the natural slope; the earth being retained by a facing of sods, &c.

I would offer that the “etc.” mentioned here included gabions.

OK, that’s the height of the traverse… what about the length needed?

When the salient of the work is arranged for defense, the traverse cannot be extended to the salient angle; it is usual to change its direction within some yards of the salient, and unite it with the face most exposed.

Keep in mind the traverse outlined above was designed to counter reverse fire on a face.  We mentioned traverses also worked to stop enfilading fire.  So more traverses were needed in the works:

Traverses are also used to cover the faces exposed to an enfilade fire; for this purpose they are placed perpendicular to the face to be covered. If several are required, they may be placed twenty or thirty yards apart; each traverse should be about twenty-four feet long, and thick enough to be cannon proof.

With all that figuring in place, the engineer could start pointing out were the shovels should go to work.

Keep in mind this process applied to the open works (with the open gorge).  The same could be used for enclosed works, with a few other considerations.  Next week, we’ll look at those along with some other “tips” offered by Mahan.

(Citation from Dennis Hart Mahan, A Treatise on Field Fortifications, New York: John Wiley, 1852, page 28-30.)

Summary Statement: December 31, 1862 – 1st New York Light Artillery Battalion

The next set of entries for the state of New York in the fourth quarter Summary Report includes one line for a section integrated with the 3rd New York Cavalry and four lines for the 1st Battalion, New York Artillery.  These need some explanation, which I’ll provide in line with the discussion of the entries.

0059_Snip_Dec62_1NY_BN_1

The first to discuss is this entry for “Artillery Detachment 3rd Cavalry“.  I think this references a unit also known as Allee’s Howitzer Battery.  As indicated the battery, or more properly a section, supported the 3rd New York Cavalry then at New Bern, North Carolina.  The section reported two 12-pdr mountain howitzers.  Such matches in general terms to newspaper accounts mentioning mountain howitzers associated with that cavalry regiment.

The next set of lines covers the “1st Battalion Artillery”.  And there are some twists here to consider.  The battalion was recruited starting in July 1861 by Lieutenant-Colonel Andrew Brickel, a former German officer from Baden (sometimes erroneously mentioned as Brickell.  I go with the name as written on his tombstone).  As it was one of the “ethnic” formations, it was often mentioned as Brickel’s German Artillery.  The battalion had four batteries – A, B, C, and D.  The battalion was part of the Army of the Potomac’s Artillery Reserve, initially part of the Fifth Corps.  During the Fredericksburg Campaign, the battalion was still part of the reserve, but at that time separate from the corps structure.  In March 1863, the battalion was discontinued and the four became independent batteries.  We have two returns transcribed into the summaries, and I’ll try to fill in a few of the blanks:

  • Battery A: At Falmouth, Virginia with four 20-pdr Parrott Rifles.  In March it became the 29th Independent Battery.
  • Battery B: No return.  The battery reported four 20-pdr Parrotts during the Antietam Campaign and presumably had the same at the end of the year.  Battery B became the 30th Independent Battery.
  • Battery C:  No return.  Another with four 20-pdr Parrotts at an earlier time in 1862.  This battery became the 31st Independent Battery.
  • Battery D:  Reporting at Martinsburg, (West) Virginia with six 3-inch Ordnance Rifles.  This was Captain Charles Kusserow’s battery and would become the 32st Independent Battery.

 

I’ve always put an asterisk next to Kusserow’s battery. The battery employed six 32-pdr field howitzers at Antietam.  Most secondary sources indicate Kusserow had 3-inch rifles at Fredericksburg.  And in discussions with some individuals knowledgeable on Fredericksburg, they often go back to this summary as to Kusserow’s guns.  I would point out the entry line indicates the return was received in June 1864.  At that time the battery, then the 32nd Independent, was indeed at Martinsburg.  Likewise, when we proceed forward in the paperwork, the summary for 1st quarter, 1863 indicates the same particulars – at Martinsburg with six 3-inch rifles, reporting in June 1864.

Again, we have a question about the entry as a point in time – was this a report indicating the armament of the battery valid for December 1862?  Or as was in June 1864?  When did Kusserow’s gunners trade in the 32-pdrs for 3-inch rifles?  (A quick check with Peter Glyer confirms that Kusserow had 3-inch rifles at Fredericksburg, so the exchange had to be between the end of September and start of December, 1862.)

None of the batteries carried smoothbore ammunition on their returns:

0061_Snip_Dec62_1NY_BN_1

I can understand those with the big Parrotts, but the mountain howitzers with the 3rd Cavalry should have something here.  And of course we have questions about Battery D’s entry already mentioned above.

For Hotckiss rifled projectiles, we have one entry line:

0061_Snip_Dec62_1NY_BN_2

Battery D reported 120 canister and 255 bullet shells of Hotchkiss patent for 3-inch rifles.  Again, put a grain of salt there. A little more “fun” with the page covering Dyer’s and Parrott patent projectiles:

0062_Snip_Dec62_1NY_BN_1

Battery A reported 155 shell, 229 case, and 80 canister of Parrott-type for their 20-pdrs. Battery D had 245 3-inch Dyer shrapnel (case) in their report.

Moving to the Schenkl columns:

0062_Snip_Dec62_1NY_BN_2

Battery A had 48 3.67-inch (20-pdr) Schenkl shells.  Battery D had 600 3-inch Schenkl shells. And those two batteries were the only representation on the small arms section:

0062_Snip_Dec62_1NY_BN_3

Battery A reported 19 Army revolvers and 54 horse artillery sabers.  Battery D was armed with 10 Army revolvers, 49 cavalry sabers, and 24 foot artillery sabers.

Seventeenth Annual Appomattox CH / Longwood U. Civil War Seminar

This year’s Civil War Seminar, hosted by Appomattox Court House National Historic Park and Longwood University is on Saturday, February 6, 2016.  As in the past few years, the place to be is Jarman Auditorium on the Longwood University campus, Farmville, Virginia.

This year’s focus is “After Appomattox.”  Speakers and schedule are:

  • 8:30 AM – Doors open.
  • 9:00 AM – Introduction by Dr. David Coles.
  • 9:10 AM – Ernie Price – Marching out of Formation: Confederates Going Home after Appomattox.
  • 10:15 AM – Patrick Schroeder – Appomattox: After the Surrender to 1865.
  • 11:15 AM – Rick Hatcher – Return to Fort Sumter.
  • 12:30 PM – Lunch.
  • 1:45 PM – Frank O’Reilly – Uneasy Alliance: Brokering Peace with Grant and Lee.
  • 2:45 PM – Eric Wittenberg – Wade Hampton and Joshua Chamberlain: Parallel Lives Well Lived.

So we see the seminar organizers are keeping somewhat with their sesquicentennial themes, and building upon the outstanding 2015 seminar (and what a grand three-day event that was!).  Though returning to the one-day format.

The cost is right in your range…. Free!

More details on the event website (here).  Hope to see you there.  If not, I’ll be doing my regular tweeting from the event… so join me virtually if you cannot attend in person.

Fortification Friday: Marking “Planes of Direct Defilement” on the Parapets

No doubt some readers are still battling with snow this Friday, with large berms of the white stuff piled high.  I’ve considered taking advantage of this to build our own little fortification with relief, Mahanian style.   But I must admit, despite encouragement… and bribery… I’ve yet to enlist my aide-de-camp to pose with a picket post in order to properly establish our fortification.  It is difficult enough just to get the aide to shovel the snow in the first place.  Seems it is much more fun to simply sled down the berm and assail neighborhood compatriots with snowballs.  Nobody wants to build up some intricate snow-works.  So, alas, readers will not have a depiction of relief in snow.

This week we will continue with Mahan’s lesson on building the relief of works. Thus far we’ve considered the need for relief in the works, defined defilement of the works,  and then begun planning the extents of that defilement.  Recall that by this point, the engineer has the basic idea of where he should place the traverse… as in this diagram:

PlateIIFig17A

Next the engineer needed to focus on the points e and e’ (again keep in mind the upper-case, lower-case distinctions here).  That brings us back to Figure 16 and the trace of the works:

PlateIIFig16A

Working on that plane, Mahan called for the engineer to address another set of planes… the planes of direct defilement.

Poles (Fig. 16) are planted at the points A B C, &c., and one at the point F, where the lines of the capital and gorge intersect.  On the pole F, a point is marked three feet above the ground and a point is likewise marked on the pole at C, which should be one foot six inches higher than that on F; that is, if the ground between the two poles be level, the point on C will be four feet six inches above the ground. Two stout pickets may next be planted between F and C, and a cord, or a straight edge, be fastened to them, so as to be in the same line as the points marked on the poles.

So let me dress up this figure to highlight what Mahan was referring to:

PlateIIFig16B

The blue lines are the posts at F and C.  The green are the two posts Mahan required on the line between F and C.  And the thin yellow line is the cord run between all four posts.  Due to the size and limitations of my graphical arts skills, I am not accurately demonstrating the height of the marks on those posts.  Keep in mind the desired marks for F (three feet) and C (four and a half, plus the height of the parapet).

These poles and cord in place, the engineer had a base line for further definition:

Observers are then placed at the poles A and B; and another places himself behind the cord [between F and C] so as to bring the posts O, A, and B, in the field of vision with it; then shifting the position of the eye until the cord is brought tangent to the highest point on O, he directs the observers at A and B, to mark on the respective poles the points where the plane of vision intersects them.  This operation will determine the rampant plane for one half of the work A B C F, and that for the other half will be determined by a similar process.  If the distance of five feet be set off on each pole above the points thus determined, these points will fix the position of the interior crests.

Looking at the diagram, let me attempt to illustrate this effort:

PlateIIFig16C

The poles at A and B are orange lines.  The line of observation, from the cord to O is in red.  Then we have the adjustments on B with the red arrows on that line.   With marks on the poles at A and B set, and a line (presumably another cord) between those posts, we set the height required for the parapet, specifically the interior crest in order to provide protection to the defenders.  The same could be repeated for D and E and set the height required on that side.  But there’s a catch here:

It is obvious that the interior crest of the part A B C is not the same plane as that of the part C D E.  These two planes are denominated planes of direct defilement.

Thus it may be that the interior crest on one side is higher than the other.  The engineer needed to “reconcile” or, simply ease the difference where the two planes come into contact on the parapet… that being at point C.  Thus there is an irregularity in the height of the parapet, which Mahan would address at a later point. But readers should keep this “conundrum” in mind as we go forward.

The poles, cords, and marks indicated here allowed the engineer to specify how much earth needed to be piled to make the parapet effective.  The verbiage used here is indicative of the desired effect – to intercept fires from the distant, high ground.  Thus we have “planes of direct defilement” here.  Next we need to look at the other side of this… that being the “planes of reverse defilement” and the details of the traverse.

Now, I ask, are you getting the feel for how complicated “pile it higher” really is?

(Citation from Dennis Hart Mahan, A Treatise on Field Fortifications, New York: John Wiley, 1852, page 27-8.)